MECHANICAL AIDS IN STEM ANALYSIS 



By Ernest C. Pegg 

 Assistant Professor of forestry^ University of Missouri 



All foresters are confronted with the monotony of stem analysis, 

 both in the field and in the office, but the work must be done if one 

 undertakes to manage a forest. The purpose of this article is to make 

 suggestions for lessening the labor connected with stem analysis, 

 especially office computations. These suggestions are based on ex- 

 perience in cordwood and tie operations in the Ozark region of southern 

 Missouri. 



The principal measurements required in the field are : stump height, 

 length of each section used, length of tip, the diameter, bark thickness, 

 and radius of decades counted from the bark to the pith at each cross- 

 cut. 



For measuring lengths, graduate the back edge of the beam of the 

 calipers, the graduations increasing toward the fixed arm. The beam 

 may then be used to measure all lengths with sufficient accuracy. 

 When cordwood or ties are being cut, the sections are uniform as to 

 length, so that the used length is determined by the number of sec- 

 tions. Only the stump and tip need be measured to determine the total 

 height. 



Since the bark is more or less broken by the saw on many cuts, it is 

 advisable to measure the diameter outside the bark with calipers, taking 

 the average of two measurements made at right angles. Measure the 

 diameter inside the bark in the same manner, using a steel rule. If the 

 rule is furnished with a sharp point at one end, stick the point in the 

 pith and swing the rule around to the average radius and draw a line 

 along the edge ; then count the rings from the outside in and measure 

 from the inside out. A fairly strong magnifying glass is of consider- 

 able assistance in counting the rings on slow-growing trees, such as 

 post-oak and black-jack oak. 



A 20-inch slide-rule and an adding-machine are two very important 

 assistants in the office. 



Suppose the total volume of the tree is desired in cubic measure. 



(B B;/\ B;;/;3 



--^+B, + B3+ .... +-:7-j/i2 H — -— 



682 



